A printed circuit board (PCB) is a composite of organic and inorganic materials with external and internal wiring, allowing electronic components to be mechanically supported and electrically connected. A PCB typically contains multiple insulation layers sandwiched between metal layers. A typical PCB contains at least one metal layer that is patterned to transfer signals between the electronic components, one power plane for distributing voltage throughout the PCB, and one ground plane.
The method and manner in which components are attached to a PCB has changed as integrated circuits and circuit board technology has improved. Today, a significant number of components are surface mounted to the PCB while others have pins soldered into plated-through-holes. In surface-mount technology, the components are soldered directly to the surface of a PCB, in contrast to the through-hole mode in which the component leads are inserted through a PCB. The driving force for the use of surface-mount technology is the reduced package size, improved utilization of board real estate and assembly simplicity.
As integrated circuit technology has improved, substantially greater functionality has been incorporated into the devices. In addition, the portability of computing and information management is driving the reduction in size from desktop to laptop to notebook sized products. Hence, as integrated circuits have expanded in functionality, the size of the devices have diminished resulting in higher clocking frequencies and increased power consumption. As a consequence, the integrated circuit devices of today generate more heat while possessing smaller surface areas to dissipate the heat. To improve thermal efficiency, many package designs today employ additional methods to dissipate heat during the operation of the integrated circuit device. One method includes the use of a heat slug that is coupled to the integrated circuit device package or directly to the integrated circuit device itself. In some applications the use of a heat slug by itself is insufficient because it lacks the thermal mass necessary to remove the heat generated by the electronic device. As a result, additional heat removal devices, such as heat pipes, are being used to supplement the heat removal capacity of the heat slug. Moreover, the manufacturing and assembly costs associated with the current methods of attaching a heat removal apparatus to an integrated circuit package is high.
What is needed then is a method which solves the aforementioned problems associated with removing heat from an integrated circuit device. As will be seen, the present invention provides a low cost method of coupling a heat slug to a PCB and an integrated circuit device using surface mount technology.